Teacher manual for AP* and Advanced Chemistry labs. Has both the printed version and a flash drive with teacher tips, a PDF of teacher version and editable Word student version.
Buffers are solutions that are resistant to changes in their pH when acids or bases are added. For example, human blood contains the bicarbonate ion. This ion can accept hydrogen ions to remove excess acidity in the blood or can donate hydrogen ions to remove alkalinity in the blood. Once the bicarbonate ions are used up, blood can rapidly become either too acidic or too basic. In other words, the bicarbonate buffer system in blood has a limited capacity.
How are buffers made, and what determines their capacity?
Students analyze the nature of buffers as they prepare buffer solutions of a specified pH and test their efficacy.
The student can design a buffer solution with a target pH and buffer capacity by selecting an appropriate conjugate acid-base pair and estimating the concentrations needed to achieve the desired capacity.
This experiment may require software and an interface for data collection.